Floor polisher drive connection

ABSTRACT

A drive connection for a floor polisher which permits ready removal from an attachment of brush units to the vertical shaft driven by the motor. The drive connection includes an annular plate element, which is secured to the brush unit, the plate element being adapted to be locked against a circular flange carried by the shaft, the shaft having lugs which pass through radially extending recesses in the annular plate element and turn in behind the annular plate element. On its rear face, the annular plate element has lug engaging ramps which terminate at lug abutments, the ramps being formed by flexible strips which are normally held away from the rear face adjacent the abutments by urethane plugs received in bores under the flexible strips.

United States Patent Inventor Bohiunil Jerabek Scarborough, Ontario,Canada Appl. No. 5,828

Filed Jan. 26, 1970 Patented Aug. 24, 1971 Assignee Dustbane EnterprisesLimited Ottawa, Ontario, Canada FLOOR POLISHER DRIVE CONNECTION 49 R, 50R, 98, 320; 287/103 R, I03 A; 51/177 [56] Referencs Cited UNITED STATESPATENTS 2,561,279 7/1951 Holt 15/49 R Pn'mary ExaminerEdward L. RobertsAttorney-Weir, Marshall, MacRae & Lamb ABSTRACT: A drive connection fora floor polisher which permits ready removal from an attachment of brushunits to the vertical shaft driven by the motor. The drive connectionincludes an annular plate element, which is secured to the brush unit,the plate element being adapted to be locked against a circular flangecarried by the shaft, the shaft having lugs which pass through radiallyextending recesses in the annular plate element and turn in behind theannular plate element. On its rear face, the annular plate element haslug engaging ramps which terminate at lug abutments, the ramps beingformed by flexible strips which are normally held away from the rearface adjacent the abutments by urethane plugs received in bores underthe flexible strips.

FLOOR POLISHER nnrvr: (ibNNECI'ION BACKGROUND OF THE INVENTION In floormaintenance machines commonly called floor polishers, it is importantthat one type of brush or buffer unit be readily removed and replaced byanother so as to enable the machine to be used for difl'erent operationsin floor care. It is also important that the change can be done quicklyand that the coupling be capable of standing up to repeated changesparticularly in the heavy duty machines used by janitorial services inlarge buildings.

A common type of coupling now utilized, includes a circular flange onthe vertical motor driven shaft of the machine, the

flange having a coaxial projection extending below; the flange ration toprovide a top surface for engagement with the flange of the verticalshaft and an oppositely'dispos'ed rear face. The plate element definesan opening for mating reception of the axial projection of the shaft andhas a plurality of radially extending recesses spaced circumferentiallyabout the opening for passage of the lugs on reception of the projectionin the opening. A plurality of lug-engaging abutment means arecircumferentially spaced about the opening and project axially fromthe-rear face, the abutment means having equal spacing to the recessesand being associated one each with the receaes. Ramp meansare providedon the rear face for engagement with the lugs and extend from eachrecess to the aslimit the turning of the plate member relative to theflange, the

plate member has solid ramps cast on the rear face, so that the lugsslide up the rampsuntil the lugs jam tight against. the ramps as the.annular plate is brought into tight engagement with the flange.

This known type of coupling has definitedisadvantages. The coupling isdesigned relative to the direction of rotation of the shaft so thatrotation tends to tighten the coupling. The high starting torquefrequently causes the plate member to become so tightly wedged, however,that when it is'desired to change the brush unit, it cannot be removed.Sincethe coupling is located between the brush unit and motor within theframeor housing of themachine it is substantially impossible for theoperator to apply the proper forces tothe coupling to loosen it when itbecomes wedged in this manner. Accordingly,'considerable operation timeof the machine and its operator may be lost. The jamming of the lug withthe ramp, whether caused by the high starting torque or-by the manner inwhich the coupling is'put together by the operator may very quicklycause deterioration of the lugs and ramps. Moreover, unless I thespacing of the lugs and ramps are very accurately formed,

one ramp may also be subject to a more severe wedging action with theresult that one or moreof theramps become seriously.

gouged. When the ramps or lugs become worn in this manner,

the wedging effort is lost so that a tight coupling is not possible, andas a result the connection may chatter and vibrate sufficiently toresult in a poor finish on the floor and serious wear and damage withinthe machine.

Various attempts have been made to improve the abovedescribed couplingwhich has become a standard connecting means on many floor polishers.One attempt'invelves the substitution of a leaf spring means for theramp, the spring being secured to the plate member at one end andsloping away from the plate member to form a resilient ramp. This designwas selected to provide a self-levelling coupling for better operationwhenthe brushes become womior when the machine is used on an irregularsurface. This type of coupling is not believed satisfactory, however,since as the plate member is turned to a coupling position, the lugsride out onto the free cantilevered ends of the leaf springs whichprovide little resistance to relative movement between the lugs and theplate member so that a firm connectiomwhich is believed necessary inview of the presence of severe vibrations, is not obtained.

SUMMARY According to one aspect of the present invention, the plateelement, which forms one member of the coupling and is adapted to besecured to the brush unit, is of annular configusociated abutment means,each ramp including a flexible strip secured at one end to the rear faceadjacent one of the recesses and defining a lug engaging ramp extendingto a free end located adjacent the associated abutment means, and acompressible spring unit contained in a bore under the free end andprojecting from ,the rear face in an uncompressed state for holding thestrip at an incline relative to the rear face.

Inv the present invention, the locking of the two separable memberstogether does not depend on the lugs wedging against a solid ramp as inthe commonly used devices. The lugs ridesmoothly up the flexible stripsand thereby compress the spring units so as to enable the lugs to abutthe axially projecting' abutment means. Accordingly, the members cannotbecome jammed and no deterioration of the. lugs and ramps occurs becauseof gouging and vibration. Moreover, as the members are tunedto acouplingposition the lugs approach and move over the spring unitslocated uncler the free ends of the flexible strips so that resistanceto tuming increases as the lugs approach the abutment means to therebyprovide a firm connection.

Preferably, the spring units consist of plugs of urethane which havegood resilient characteristics not effected by the BRIEF DESCRIPTION OFTHE INVENTION Other features'and advantages of the invention will becomeapparent from the following description of the preferred embodiment ofthe invention with reference being made to the accompanying drawings inwhich:

FIG. 1 is a partially sectioned, elevational view of a floor polisherincorporating the coupling of the present invention;

FIG. 2 is a perspective view showing the bottom or rear face of onemember of the coupling;

FIG. 3 is a cross-sectional view taken along the line III-III of-FIG. 2;and a FIG. 4 is a perspective view of the interconnectable membersforming the couple, one member being removed from the other.

DESCRIPTION OF PREFERRED EMBODIMENTS v14, which forms the presentinvention, is a brush unit 15.

Although unit 15 is referred to as a brush unit and is shown as such inthe drawings, it is apparent that it may be in the form of a buffing pador similar attachment used in floor maintenance.

As shown most clearly in FIG. 4, the shaft 13 is provided at its lowerend wit a circular flange, 16 which is fixed relative to the shaft incoaxial relation. The flange 16 presents a horizontally disposed, flat,annular bottom surface 17. Coaxially disposed within the annular bottomsurface 17 is a projection or hub 20 of circular cross section, andfonned integrally with the hub 20 and extending radially therefrom arelugs 21. The lugs 21 are equally spaced about circumference of the hub20 and are axially spaced from the annular bottom surface 17. The shaft13, flange 16,hub 20 and lugs 21 may be cast as an integral unit andform one member of the coupling 14.

The other member of the coupling includes a flat annular plate elementor member 22. The annular plate member 22 defines a forward or topsurface 23, which may have substantially thesame dimensions astheannular bottom surface 17, and a rear face 24. The annular plate member22 has a central opening 25 of a size to closely receive the hub 20, andthe thickness of the annular plate member is slightly less than theaxial spacing between the lugs 21 and the bottom annular sur face 17defined by the circular flange.

Extending radially from the central opening 25 are a plurality ofcircumferentially spaced recesses 26 which are equal in number andspacing to the lugs 21 and which are shaped to permit passage of thelugs when the hub 20 is received in the central opening 24. Associatedwith each recess and spaced a distance around the periphery in theclockwise direction as viewed in FIG. 2 is an abutment means or stop 27in the form of a projection extending axially fromthe rear face 24. Eachstop 27 has a lug engaging side 28 facing the associated recess thereof,the side 28 projecting substantially perpendicular from the rear face24. a

A ramp means 30 extends from each recess 26 to the associated stop27..The ramp means includes a flexible strip 31,

preferably formed of steel, and being relatively thin in comparison toits width. Each flexible strip 31 is of arcuate shaped so as to curveabout the central opening 25 from a fixed end 32 adjacent the recess 26to a free end 33 terminating at the lug engaging side 28 of theassociated stop. The fixed end 32 is securedflatly against the rear face24 by way of rivets or screws 34 received in appropriate bores in theannular plate member 22.

Located under the free end 33 of each flexible strip 31 is a blind bore35. The bore 35 has a main outer section 36, and an inner section 36 ofsmaller cross section, and is preferably in the form of a common borewhich terminates in conical inner section as shown in FIG. 3. Receivedin the bore 35 is a resilient means or compressible spring unit 37 whichpreferably consists of a simple cylindrical plug 40 of urethane The plug40 is slightly'smaller in cross section than the main section 36 of thebore and is closely received in the bore. Although the plug 40 isclosely received in the main section 36 of the bore, it need not betightly received, and the plug 40 is of greater length than themainsection 36 so that it projects from the rear face 24 in an uncompressedstate so as to hold the free end away from the rear face 24.Accordingly, whenthe annular plate member is uncoupled, the flexiblestrips 31 slope noticeably away from the rear face 24 to define lugengaging ramps.

The annular'plate member 22 is secured to the top of the brush unit byway of screws or similar means passing through bores 41 so that brushunit and annular plate members turn as a unit. The operation ofconnecting the brush unit 15 to the shaft 13 so that the brush unit willbe driven by shaft [3 simply involves holding the brush unit so thatannular plate member 2 2 is brought up to hub 20, orienting the annularplate member to permit the lugs 21 to pass through the recesses 26 asthe hub is received in the central opening 25, and then rotating theannular plate member as the surface 23 of the annular plate memberengages the bottom surface 17 of circular flange 16 until lugs 21 engagesides 28 of stops 27. During the last step of rotating the annular platemember 22, which step is carried out by turning the brush unit, thenheld in the hands of the operator, through a fraction of a revolution,the lugs slide along the ramp means 30 as each lug travels towards theassociated stop 27. Initially, the turning torque required to turn theannular plate member 22 relative to the circular flange 16 issubstantially negligible as the lugs slide freely over the strips 31. Asthe lugs approach the stops 27, the

- nular plate member 22 and circular flange 16 so that nostrips 31,which are pressed towards the rear face 24, apply pressure to the end ofthe plugs 40.,When each plug 40 is initially compressed, itscross-sectional area enlarges so as to completely fill the main outersection 36 of the bore. During further rotation, each lug slides alongthe strip, which at this stage presents a rather steep ramp, and ontothe portion of the strip immediately over the plug. The turningresistance increases during this stage since, due to the nature ofurethane, the plug begins to flow down into the inner section 36, anddue to the tapered shape of the innersectio'n 36' into which the plugflows, the increase is gradual. The'size of the plug is selected,however, so that even as each lug approaches the side 28 of theassociated stop, the turning resistance is not great. Preferably, theplug is of sufficient volume to completely fill the bore and to overflowslightly when each lug has been brought against the associated stop. Theportion of the plug which overflows around the rim of the boresignificantly aids in forming a positive and vibrationless lock betweenthe annu-. lar plate member 22 and the shaft 13.

As the spring units are compressed as described above, the couplingbecomes very firm since the top surface 23 is forced into tightengagement with the bottom surface 17 of the circular flange by way ofthe reactionary forces. Nevertheless, unlike known couplings, the sameturning force is used to complete the connection each time the brushunit is attached.

When the brush unit is to be removed, it is simply grasped, turned backuntil the lugs reach the recesses 26 and then pulled away from the shaft13. When the lugs ride away from the spring units 37, the urethane plugsregain their original shape. Again, as when the coupling is being made,the same turning force is required each time the brush unit is removed.

The annular plate member 22 cannot become wedged in a coupling positionin spite of high torques which might be transferred through the couplingwhen the machine is started or when the brush unit encounters variedresistance during operation. Such torques are simply transferred fromthe lugs 21 to the stop 27. Moreover, since a firm coupling is providedand the connection does not depend on a wedging efiect, vibrations andchatter are substantially eliminated and loosening of the connectiondoes not occur. When the coupling is subjected to an unbalancedpressure, such as when the operator of the floor machine alternatespressure on the handle to move the machine from side to side or when themachine is tilted to apply increased pressure on heel marks or spotsrequiring increased pressure, the urethane plug, and particularly theportion thereof which has spilled over and is flattened between thestrip and the rear face of the annular plate member, eliminates thepossibility of any clearances occurring between the parts. In otherwords, the urethane provides a resilient and yet firm pressure betweenthe surfaces of the anchatter can take place.

The urethane plugs have been found superior to other types of springsbecause of the good resilient characteristics of urethane and itsability to avoid deterioration even though it may be continuallysubjected to moisture and chemicals such as detergent. Moreover, suchplugs are extremely economical to produce.

The embodiment shown in the drawings is shown to illus-- trate oneexample of the invention, it being apparent that various otherstructural arrangements could be utilized. For example, instead ofhaving hub 20, the shaft 13 could be provided with an annular portionprojecting axially therefrom, the annular portion having the lugsprojecting radially inwardly therefrom. The other member could then takethe form of a circular plate member provided with inwardly extendingrecesses about the periphery thereof. The ramp means and the associatedstop means would then be located on the rear face of the circular platemember immediately within the periphery thereof.

Furthermore, although the coupling of the present invention has beenillustrated in conjunction with the drive of a floor machine, it isobvious that it could be utilized with like advantages in otherenvironments for connecting one member to another, such as in drivesystems of other machines where it is desirable to uncouple a drivenelement.

I claim:

1. A coupling comprising first and second joinable members havingengageable surfaces, said first member having an element projectingaxially from the surface thereof and providing a plurality ofcircumferentially spaced, radially extending lugs axially spaced fromthe surface of the first member, said second member being in the form ofa flat plate element of a thickness less than the axial spacing betweenthe lugs and the surface of the first member, one of said elements beingof circular configuration and the other being of annular configurationto define a circular opening for coaxial mating reception of said oneelement, said plate element having a plurality of circumferentiallyspaced recesses disposed for passage of said lugs as said one element isreceived in said other element, a plurality of lug abutment meansprojecting axially from a rear face oppositely disposed on said plateelement as the engageable surface of said second member, each abutmentmeans being associated with one of said recesses, a plurality offlexible strips each being secured to said rear face at a first end andextending away from one of the recesses to a free end adjacent theassociated abutment means, said rear face having a plurality of borestherein located one each under the free end of each flexible strip, aplurality of compressible resilient members contained one each in thebores and in an uncompressed state projecting from said rear face tohold the free end of the strip away from said face, said strips therebydefining lug-engaging ramps so that as said one element is inserted inthe opening defined by the other element, the lugs pass through therecesses and as one of said members is rotated relative to the other,said lugs of said first member ride up the flexible strips behind therear face of the second member and thereby compress the resilient memberand engage said abutment means.

2. A coupling comprising first and second members to be joined incoaxial relationship, said member defining engageable annular surfaces,said first member having a central element projecting axially from theannular surface thereof, a plurality of circumferentially spaced lugsprojecting radially from said central element and being axially spacedfrom the annular surface of said first member, said second member havinga flat annular plate portion of a thickness less than the axial spacingbetween said lugs and the annular surface of said first member, saidplate portion defining a central opening and having a plurality ofcircumferentially spaced recesses projecting radially from said openingfor passage of said lugs, said plate portion having a face on anopposite side thereof as said annular surface with abutment meansprojecting axially from said face about said openings, a plurality oframp defining flexible strips each secured adjacent a first end thereofto said face adjacent an associated recess and extending from theassociated recess to an associated one of said abutment means, eachstrip having a second end thereof adjacent the associated abutment andfree to flex relative to said face, said face having a plurality ofblind bores therein one each under the free end of one of said strips, aplurality of compressible resilient members one each in said bores andin an uncompressed state projecting from said face to hold the free endof the strip away from the face whereby each strip defines a lugengaging surface sloping upwardly relative to the face from theassociated recess towards the associated abutment means.

3. A coupling as defined in claim 2, wherein each of said resilientmembers comprises a urethane plug.

4. A coupling as defined in claim 2, wherein each of said bores has amain section of circular cross section and a lower conical section. andwherein said resilient member consists of a cylindrical plug or urethanefor close reception in said main section and having a greater lengththan said main section.

5. A coupling as defined in claim 2, wherein said flexible 'strips arearcuately shaped steel members each defining a ramp which curves about aportion of the periphery. of the central opening ofsaid second member.

6. In a floor machine of the type having a motor carried on a frame anda floor engaging brush unit mounted to rotate below the frame about avertical axis; the improvement of a releasable drive coupling forconnecting said brush unit to a drive output of-said motor, said drivecoupling comprising a first member including a vertically disposed,motor-driven shaft, a circular flange formed integrally with said shaftand defining a horizontally disposed annular surface, a coaxial hub ofcircular cross section extending below said annular surface and having aplurality of lugs projecting radially therefrom in axial spaced relationbelow said annular surface, a second member secured to the brush unitand including a flat annular plate element having a top surface forengagement with said annular surface of said first member, said plateelement being of less thickness than the axial spacing between said lugsand said annular surface of said first member and having a rear faceopposite to said top surface, said annular plate element defining acentral opening for mating reception of said hub of said first memberand having a plurality of radially extending recesses spacedcircumferentially about said opening for passage of said lugs duringreception of said hub in said opening, a plurality of lug engagingabutment means spaced about the central opening and projecting downwardfrom said rear face, each abutment means being associated with one ofthe recesses, and a ramp means extending from each recess to theassociated abutment means for engagement with one of said lugs duringrotation of said second member relative to said first member afterpassage of said lugs through said recesses,- each ramp means includingan arcuate shaped flexible stripsecured to said rear face at one endadjacent one of the recesses and defining a lug-engaging ramp curvedabout a portion of the periphery of said central opening to a free endlocated adjacent the associated abutment means, said rear face having abore under the free end of each strip, and a plug of urethane containedin each bore and projecting from said rear face for urging said free endof said strip away from said rear face.

7. A drive coupling as defined in claim 6, wherein said bore has anouter main section of circular cross section and an inner conicalsection, and wherein said urethane plug is of cylindrical shape forclose reception in said main section and has a length greater than saidmain section.

8. A coupling member for a brush unit in a floor machine of the typehaving a frame carried motor and a depending motor drive shaft havingcircuit flange formed integrally with said shaft, the shaft including anaxial projection of circular cross section extending below the circularflange and a plurality of lugs projecting radially from the projectionin axial spaced relation to the circular flange; said coupling membercomprising a flat annular plate element for securement to said brushunit, said plate element having a top surface for engagement with saidcircular flange and an oppositely disposed rear face, said plate elementdefining a central opening for mating reception of said axial projectionof said shaft and having a plurality of radially extending recessesspaced circumferentially about said opening for passage of said lugs onreception of said projection in said opening, a plurality of lugengaging abutment means circumferentially spaced about said opening andprojecting axially from said rear face, said abutment means having equalspacing to saidrecesses and being associated one each with saidrecesses, and a ramp means on said rear face and extending from eachrecess to the associated abutment means, each ramp means including aflexible strip secured at one end to said rear face adjacent one of therecesses and defining a lug-engaging ramp extending to a free endlocated adjacent the associated abutment means, said rear face having abore under each free end, and a compressible spring unit contained ineach bore and projecting from the rear face in an uncompressed state forholding said flexible strip in a sloping relation to said rear face.

9. A coupling member as defined in claim 8, wherein the flexible stripis an arcuate-shaped member formed of steel and curving about a portionof the periphery of the central opening, and wherein said spring unit isa plug or urethane.

cross section than the main section, said plug having a cross.

section substantially as great as said main section and being of greaterlength than said main section.

11. A coupling member as defined in claim 9, wherein said bore.

' plug has a volume slightly greater than the total volume of the

1. A coupling comprising first and second joinable members havingengageable surfaces, said first member having an element projectingaxially from the surface thereof and providing a plurality ofcircumferentially spaced, radially extending lugs axially spaced fromthe surface of the first member, said second member being in the form ofa flat plate element of a thickness less than the axial spacing betweenthe lugs and the surface of the first member, one of said elements beingof circular configuration and the other being of annular configurationto define a circular opening for coaxial mating reception of said oneelement, said plate element having a plurality of circumferentiallyspaced recesses disposed for passage of said lugs as said one element isreceived in said other element, a plurality of lug abutment meansprojecting axially from a rear face oppositely disposed on said plateelement as the engageable surface of said second member, each abutmentmeans being associated with one of said recesses, a plurality offlexible strips each being secured to said rear face at a first end andextending away from one of the recesses to a free end adjacent theassociated abutment means, said rear face having a plurality of borestherein located one each under the free end of each flexible strip, aplurality of compressible resilient members contained one each in thebores and in an uncompressed state projecting from said rear face tohold the free end of the strip away from said face, said strips therebydefining lug-engaging ramps so that as said one element is inserted inthe opening defined by the other element, the lugs pass through therecesses and as one of said members is rotated relative to the other,said lugs of said first member ride up the flexible strips behind therear face of the second member and thereby compress the resilient memberand engage said abutment means.
 2. A coupling comprising first andsecond members to be joined in coaxial relationship, said memberdefining engageable annular surfaces, said first member having a centralelement projecting aXially from the annular surface thereof, a pluralityof circumferentially spaced lugs projecting radially from said centralelement and being axially spaced from the annular surface of said firstmember, said second member having a flat annular plate portion of athickness less than the axial spacing between said lugs and the annularsurface of said first member, said plate portion defining a centralopening and having a plurality of circumferentially spaced recessesprojecting radially from said opening for passage of said lugs, saidplate portion having a face on an opposite side thereof as said annularsurface with abutment means projecting axially from said face about saidopenings, a plurality of ramp defining flexible strips each securedadjacent a first end thereof to said face adjacent an associated recessand extending from the associated recess to an associated one of saidabutment means, each strip having a second end thereof adjacent theassociated abutment and free to flex relative to said face, said facehaving a plurality of blind bores therein one each under the free end ofone of said strips, a plurality of compressible resilient members oneeach in said bores and in an uncompressed state projecting from saidface to hold the free end of the strip away from the face whereby eachstrip defines a lug engaging surface sloping upwardly relative to theface from the associated recess towards the associated abutment means.3. A coupling as defined in claim 2, wherein each of said resilientmembers comprises a urethane plug.
 4. A coupling as defined in claim 2,wherein each of said bores has a main section of circular cross sectionand a lower conical section, and wherein said resilient member consistsof a cylindrical plug or urethane for close reception in said mainsection and having a greater length than said main section.
 5. Acoupling as defined in claim 2, wherein said flexible strips arearcuately shaped steel members each defining a ramp which curves about aportion of the periphery of the central opening of said second member.6. In a floor machine of the type having a motor carried on a frame anda floor engaging brush unit mounted to rotate below the frame about avertical axis; the improvement of a releasable drive coupling forconnecting said brush unit to a drive output of said motor, said drivecoupling comprising a first member including a vertically disposed,motor-driven shaft, a circular flange formed integrally with said shaftand defining a horizontally disposed annular surface, a coaxial hub ofcircular cross section extending below said annular surface and having aplurality of lugs projecting radially therefrom in axial spaced relationbelow said annular surface, a second member secured to the brush unitand including a flat annular plate element having a top surface forengagement with said annular surface of said first member, said plateelement being of less thickness than the axial spacing between said lugsand said annular surface of said first member and having a rear faceopposite to said top surface, said annular plate element defining acentral opening for mating reception of said hub of said first memberand having a plurality of radially extending recesses spacedcircumferentially about said opening for passage of said lugs duringreception of said hub in said opening, a plurality of lug engagingabutment means spaced about the central opening and projecting downwardfrom said rear face, each abutment means being associated with one ofthe recesses, and a ramp means extending from each recess to theassociated abutment means for engagement with one of said lugs duringrotation of said second member relative to said first member afterpassage of said lugs through said recesses, each ramp means including anarcuate shaped flexible strip secured to said rear face at one endadjacent one of the recesses and defining a lug-engaging ramp curvedabout a portion of the periphery of said central opening to a free endlocated adjacent the associated abutment means, said rear face having abore under the free end of each strip, and a plug of urethane containedin each bore and projecting from said rear face for urging said free endof said strip away from said rear face.
 7. A drive coupling as definedin claim 6, wherein said bore has an outer main section of circularcross section and an inner conical section, and wherein said urethaneplug is of cylindrical shape for close reception in said main sectionand has a length greater than said main section.
 8. A coupling memberfor a brush unit in a floor machine of the type having a frame carriedmotor and a depending motor drive shaft having circuit flange formedintegrally with said shaft, the shaft including an axial projection ofcircular cross section extending below the circular flange and aplurality of lugs projecting radially from the projection in axialspaced relation to the circular flange; said coupling member comprisinga flat annular plate element for securement to said brush unit, saidplate element having a top surface for engagement with said circularflange and an oppositely disposed rear face, said plate element defininga central opening for mating reception of said axial projection of saidshaft and having a plurality of radially extending recesses spacedcircumferentially about said opening for passage of said lugs onreception of said projection in said opening, a plurality of lugengaging abutment means circumferentially spaced about said opening andprojecting axially from said rear face, said abutment means having equalspacing to said recesses and being associated one each with saidrecesses, and a ramp means on said rear face and extending from eachrecess to the associated abutment means, each ramp means including aflexible strip secured at one end to said rear face adjacent one of therecesses and defining a lug-engaging ramp extending to a free endlocated adjacent the associated abutment means, said rear face having abore under each free end, and a compressible spring unit contained ineach bore and projecting from the rear face in an uncompressed state forholding said flexible strip in a sloping relation to said rear face. 9.A coupling member as defined in claim 8, wherein the flexible strip isan arcuate-shaped member formed of steel and curving about a portion ofthe periphery of the central opening, and wherein said spring unit is aplug or urethane.
 10. A coupling member as defined in claim 9, whereinthe bore has an outer main section and an inner section of smaller crosssection than the main section, said plug having a cross sectionsubstantially as great as said main section and being of greater lengththan said main section.
 11. A coupling member as defined in claim 9,wherein said plug has a volume slightly greater than the total volume ofthe bore.